Hazard on the upper Usk at Abercamlais on the Sennybridge to Aberbran section.

Operation of temporary fish traps by Natural Resources Wales.

Rotary Screw Traps (RSTs) are temporary fish traps used to capture young salmon and sea trout on their journey to the sea. This note informs canoeists and other river users where and when they may encounter these in-river structures.

In 2024 a RST will be operated on the River Usk at Abercamlais (SN 95994 29168)

These traps come in various sizes but all consist of a rotating cone-shaped drum mounted between two floating pontoons. Operation involves the positioning of each trap in the main body of the flow where the drum is lowered into the water until half submerged. Water flowing through the mouth of the drum causes it to rotate by acting on an internal vane. The same vane moves any fish which enter the drum to the rear of the RST where they are delivered into a holding box for tagging and release.

The trap will be fished only in the Spring (March to May), and then just between the hours of dusk and dawn - when it will be manned. Warning signs will be placed upstream and on the trap itself, this will notify river users of their presence.

At Abercamlais, a straight section of river of around 170m lies immediately upstream and downstream of the trapping site and so give a good line-of-sight for river users. Bankside signage gives advanced notice of the structure with a shallow section upstream where canoeists can disembark (see Fig 1).

Contact details for Rotary Screw Traps operated by Natural Resources Wales on the River Usk:

Mid March to May

Oliver Brown

Tel: 01874 665212

Oliver.Brown@cyfoethnaturiolcymru.gov.uk